1. Field of the Invention
The present invention relates to an overvoltage protection circuit and a method thereof, and more particularly, to an overvoltage protection circuit that can be simply implemented in an integrated circuit (IC) and safely protect a circuit from an overvoltage input from the outside, and a method thereof.
2. Description of the Related Art
In recent times, electronic devices with secondary batteries, such as mobile phones and digital cameras, are being widely used. When an AC adapter is connected to such a device, the device can be operated by electric power supplied from the AC adapter and the secondary battery can be charged at the same time. As such devices have been widely used, various AC adapters having different output voltages have been used. Since limited types of connectors are available for the AC adapters, the AC adapters that output different voltages may have the same type of connector. Therefore, an improper AC adapter may be connected to an electronic device by mistake.
For example, when an AC adapter, which outputs a voltage higher than an endurance voltage of a semiconductor device of an arbitrary electronic device, is connected to the electronic device, the semiconductor device may be damaged or broken.
All circuits should operate within the specified power voltage range. A power voltage over the specified range is referred to as an overvoltage. The circuit may be shut down or breakdown of the circuit may occur due to the influence of the overvoltage. Therefore, each system uses an overvoltage protection circuit to prevent introduction of an input voltage higher than an operable power voltage. Particularly, when the overvoltage protection circuit is implemented in an integrated circuit (IC), there is a difficulty in being applied to the IC due to an increase in area by a diode, a high voltage transistor, etc.